Acting-wise Al Pacino is still joined to the hip of Dustin Hoffman although his more emotional, short-fused character is beginning to emerge in this fact-based story of an honest cop and eventual whistleblower who sacrifices all for his refusal to conform to institutionalized corruption in the NYPD.
It is subject matter very much of its time, Lumet laying the good guys vs bad guys message on very thickly (the scene in which the three good-guys whoop when they read the New York Times announcement of an inquiry seems completely over-the-top). The look of the film is also very much of its time with Pacino, who gets as shaggy as his sheepdog as the film progresses, sporting some classic wardrobe choices. At 129 mins it is somewhat long, particularly in the middle stages but it is worth staying the distance for Pacino's moving portrayal of a man fighting for his ideals. Tony Roberts, best known for his appearances in Woody Allen's films makes an unlikely compatriot for Serpico and F. Murray Abraham makes a very early and uncredited screen appearance as a crooked cop.